Application of interpolation methodology with dynamical constraint to the suspended particulate matter in the Liaodong Bay

IntroductionSuspended Particulate Matter (SPM) influences the primary production and the distributions of pollutants in the ocean. Besides, the regulation mechanisms of SPM in the Liaodong Bay were complicated.MethodTo analyze the distributions and influencing factors of SPM, based on the adjoint assimilation method, an interpolation method with dynamical constraint was established in the Liaodong Bay.ResultIn two ideal experiments, the cost function, Mean Absolute Error (MAE) and Normalized Mean Error (NME) all had reduced by more than 90%, which proved the accuracy of the interpolation method. Based on conventional observations of SPM, the distributions of dynamically constrained, Kriging and radial basis function (RBF) interpolations in March, May, August and October of 2015 were obtained.DiscussionThe cross-validation was carried out to compare the dynamically constrained interpolation and the unconstrained interpolations. Among seven unconstrained interpolation methods, the averaged MAE of RBF interpolation was the lowest, which was 10.976 mg/L. The averaged MAE of dynamically constrained interpolation was 7.703 mg/L, reduced by 29.8% compared with the RBF interpolation. It was indicated that RBF interpolation was the most accurate among the seven unconstrained interpolations and dynamically constrained interpolation was more accurate than unconstrained interpolations at the observation stations. The distributions of dynamically constrained and RBF interpolations were compared with Korean Geostationary Ocean Color Imager (GOCI) satellite-derived distributions of SPM concentrations in the Liaodong Bay. Fully considering the influences of the hydrodynamic processes, the dynamically constrained interpolation provided distributions more consistent with the satellite-derived distributions. However, due to the lack of observations in some areas and ignoring the influences of currents, some high values of SPM concentration were not captured by the distributions of RBF interpolation. Moreover, in accordance with the results of dynamically constrained interpolation, it was found that the SPM concentrations in the bay were affected by the SPM discharge from the Liao River Basin

Toxic Effects of Silica Nanoparticles on Zebrafish Embryos and Larvae

Silica nanoparticles (SiNPs) have been widely used in biomedical and biotechnological applications. Environmental exposure to nanomaterials is inevitable as they become part of our daily life. Therefore, it is necessary to investigate the possible toxic effects of SiNPs exposure. In this study, zebrafish embryos were treated with SiNPs (25, 50, 100, 200 μg/mL) during 4-96 hours post fertilization (hpf). Mortality, hatching rate, malformation and whole-embryo cellular death were detected. We also measured the larval behavior to analyze whether SiNPs had adverse effects on larvae locomotor activity. The results showed that as the exposure dosages increasing, the hatching rate of zebrafish embryos was decreased while the mortality and cell death were increased. Exposure to SiNPs caused embryonic malformations, including pericardial edema, yolk sac edema, tail and head malformation. The larval behavior testing showed that the total swimming distance was decreased in a dose-dependent manner. The lower dose (25 and 50 μg/mL SiNPs) produced substantial hyperactivity while the higher doses (100 and 200 μg/mL SiNPs) elicited remarkably hypoactivity in dark periods. In summary, our data indicated that SiNPs caused embryonic developmental toxicity, resulted in persistent effects on larval behavior. © 2013 Duan et al.published_or_final_versio

OsbZIP18, a Positive Regulator of Serotonin Biosynthesis, Negatively Controls the UV-B Tolerance in Rice

Serotonin (5-hydroxytryptamine) plays an important role in many developmental processes and biotic/abiotic stress responses in plants. Although serotonin biosynthetic pathways in plants have been uncovered, knowledge of the mechanisms of serotonin accumulation is still limited, and no regulators have been identified to date. Here, we identified the basic leucine zipper transcription factor OsbZIP18 as a positive regulator of serotonin biosynthesis in rice. Overexpression of OsbZIP18 strongly induced the levels of serotonin and its early precursors (tryptophan and tryptamine), resulting in stunted growth and dark-brown phenotypes. A function analysis showed that OsbZIP18 activated serotonin biosynthesis genes (including tryptophan decarboxylase 1 (OsTDC1), tryptophan decarboxylase 3 (OsTDC3), and tryptamine 5-hydroxylase (OsT5H)) by directly binding to the ACE-containing or G-box cis-elements in their promoters. Furthermore, we demonstrated that OsbZIP18 is induced by UV-B stress, and experiments using UV-B radiation showed that transgenic plants overexpressing OsbZIP18 exhibited UV-B stress-sensitive phenotypes. Besides, exogenous serotonin significantly exacerbates UV-B stress of OsbZIP18_OE plants, suggesting that the excessive accumulation of serotonin may be responsible for the sensitivity of OsbZIP18_OE plants to UV-B stress. Overall, we identified a positive regulator of serotonin biosynthesis and demonstrated that UV-B-stress induced serotonin accumulation, partly in an OsbZIP18-dependent manner

Thermochemical sulfate reduction in fossil Ordovician deposits of the Majiang area: Evidence from a molecular-marker investigation

The main reservoirs of Majiang fossil deposits consist of the Silurian Wengxiang group, dominantly sandstones, and the Ordovician Honghuayuan formation, dominantly carbonate rocks, and the Lower Cambrian Niutitang Formation mudstones serve as the major source rocks. Thermochemical sulfate reduction (TSR) might have taken place in the Paleozoic marine carbonate oil pools, as indicated by high concentrations of dibenzothiophenes in the extracts (MDBT=0.27-4.32 µg/g extract, and MDBT/MPH= 0.71-1.38). Hydrocarbons in the Pojiaozhai Ordovician carbonate reservoirs have undergone severe TSR and are characterized by higher quantities of diamondoids and MDBT and heavier isotopic values (δ13C=-28.4‰). The very large amounts of dibenzothiophenes might be products of reactions between biphenyls and sulfur species associated with TSR

Regulatory Feedback Loop of Two phz Gene Clusters through 5′-Untranslated Regions in Pseudomonas sp. M18

BACKGROUND: Phenazines are important compounds produced by pseudomonads and other bacteria. Two phz gene clusters called phzA1-G1 and phzA2-G2, respectively, were found in the genome of Pseudomonas sp. M18, an effective biocontrol agent, which is highly homologous to the opportunistic human pathogen P. aeruginosa PAO1, however little is known about the correlation between the expressions of two phz gene clusters. METHODOLOGY/PRINCIPAL FINDINGS: Two chromosomal insertion inactivated mutants for the two gene clusters were constructed respectively and the correlation between the expressions of two phz gene clusters was investigated in strain M18. Phenazine-1-carboxylic acid (PCA) molecules produced from phzA2-G2 gene cluster are able to auto-regulate expression itself and activate the expression of phzA1-G1 gene cluster in a circulated amplification pattern. However, the post-transcriptional expression of phzA1-G1 transcript was blocked principally through 5'-untranslated region (UTR). In contrast, the phzA2-G2 gene cluster was transcribed to a lesser extent and translated efficiently and was negatively regulated by the GacA signal transduction pathway, mainly at a post-transcriptional level. CONCLUSIONS/SIGNIFICANCE: A single molecule, PCA, produced in different quantities by the two phz gene clusters acted as the functional mediator and the two phz gene clusters developed a specific regulatory mechanism which acts through 5'-UTR to transfer a single, but complex bacterial signaling event in Pseudomonas sp. strain M18

Study of the Overflow Transport of the Nordic Sea

Changes in the climate system over recent decades have had profound impacts on the mean state and variability of ocean circulation, while the Nordic Sea overflow has remained stable in volume transport during the last two decades. The changes of the overflow flux depend on the pressure difference at the depth of the overflow outlet on both sides of the Greenland-Scotland Ridge (GSR). Combining satellite altimeter data and the reanalysis hydrological data, the analysis found that the barotropic pressure difference and baroclinic pressure difference on both sides of the GSR had a good negative correlation from 1993 to 2015. Both are caused by changes in the properties of the upper water, and the total pressure difference has no trend change. The weakening of deep convection can only change the temperature and salt structure of the Nordic Sea, but cannot reduce the mass of the water column. Therefore, the stable pressure difference drives a stable overflow. The overflow water storage in the Nordic Sea is decreasing, which may be caused by the reduction of local overflow water production and the constant overflow flux. When the upper interface of the overflow water body in the Nordic Sea is close to or below the outlet depth, the overflow is likely to greatly slow down or even experience a hiatus in the future, which deserves more attention

The Temporal Evolution of Coastlines in the Bohai Sea and Its Impact on Hydrodynamics

Over the past 40 years, increasing coastal reclamation and natural sedimentation has changed coastline positions and resulted in variation in the hydrodynamic environment in the Bohai Sea (BHS), China. Based on the Landsat series images, an interpretative identifier for identifying the coastline was proposed to assess the hydrodynamic changes caused by the coastline change and was applied to a typical case of the Bohai Sea (BHS), China. We combined a grid-based coastline position with an adjoint data assimilation method to seamlessly map the distribution of the amplitude, phase lag, and tidal current of the M2 tidal constituent along the BHS’s coast from 1985 to 2018. Our findings reveal that the coastline change at long time scales dominated reclamation, and around 72.9% of the coastline of the BHS mapped in 2018 had seaward movement compared with its position in 1985. From 1985 to 2018, the BHS volume decreased by 0.17%, the sea surface area decreased by 4.54%, and the kinetic energy increased by 2.53%. The change in the coastline increased the amplitude of the M2 tidal constituent in the Bohai Bay by 6–14 cm and increased the residual current in the eastern coast of the Liaodong Bay by up to 0.07 (0.01) m/s

The Temporal Evolution of Coastlines in the Bohai Sea and Its Impact on Hydrodynamics

Over the past 40 years, increasing coastal reclamation and natural sedimentation has changed coastline positions and resulted in variation in the hydrodynamic environment in the Bohai Sea (BHS), China. Based on the Landsat series images, an interpretative identifier for identifying the coastline was proposed to assess the hydrodynamic changes caused by the coastline change and was applied to a typical case of the Bohai Sea (BHS), China. We combined a grid-based coastline position with an adjoint data assimilation method to seamlessly map the distribution of the amplitude, phase lag, and tidal current of the M2 tidal constituent along the BHS’s coast from 1985 to 2018. Our findings reveal that the coastline change at long time scales dominated reclamation, and around 72.9% of the coastline of the BHS mapped in 2018 had seaward movement compared with its position in 1985. From 1985 to 2018, the BHS volume decreased by 0.17%, the sea surface area decreased by 4.54%, and the kinetic energy increased by 2.53%. The change in the coastline increased the amplitude of the M2 tidal constituent in the Bohai Bay by 6–14 cm and increased the residual current in the eastern coast of the Liaodong Bay by up to 0.07 (0.01) m/s